1. Field of the Invention
The present invention relates to apparel. The invention concerns, more particularly, an article of apparel incorporating zones with a textile having a structure that changes or is otherwise modified by a physical stimulus, such as the presence of water or a temperature change, to modify a property of the textile. The invention has application, for example, to articles of apparel intended for use during athletic activities.
2. Description of Background Art
Articles of apparel designed for use during athletic activities generally exhibit characteristics that enhance the performance or comfort of an individual. For example, apparel may incorporate an elastic textile that provides a relatively tight fit, thereby imparting the individual with a lower profile that minimizes wind resistance. Apparel may also be formed from a textile that wicks moisture away from the individual in order to reduce the quantity of perspiration that accumulates adjacent to the skin. Furthermore, apparel may incorporate materials that are specifically selected for particular environmental conditions. Examples of various types of articles of apparel include shirts, headwear, coats, jackets, pants, underwear, gloves, socks, and footwear.
The characteristics of the textiles that are incorporated into apparel are generally selected based upon the specific activity for which the apparel is intended to be used. A textile that minimizes wind resistance, for example, may be suitable for activities where speed is a primary concern. Similarly, a textile that reduces the quantity of perspiration that accumulates adjacent to the skin may be most appropriate for athletic activities commonly associated with a relatively high degree of exertion. Accordingly, textiles may be selected to enhance the performance or comfort of individuals engaged in specific athletic activities.
Textiles may be defined as any manufacture from fibers, filaments, or yarns characterized by flexibility, fineness, and a high ratio of length to thickness. Textiles generally fall into two categories. The first category includes textiles produced directly from webs of fibers or filaments by bonding, fusing, or interlocking to construct non-woven fabrics and felts. The second category includes textiles formed through a mechanical manipulation of yarn, thereby producing a woven fabric.
Yarn is the raw material utilized to form textiles in the second category and may be defined as an assembly having a substantial length and relatively small cross-section that is formed from at least one filament or a plurality of fibers. Fibers have a relatively short length and require spinning or twisting processes to produce a yarn of suitable length for use in textiles. Common examples of fibers are cotton and wool. Filaments, however, have an indefinite length and may merely be combined with other filaments to produce a yarn suitable for use in textiles. Modern filaments include a plurality of synthetic materials such as rayon, nylon, polyester, and polyacrylic, with silk being the primary, naturally-occurring exception. Yarn may be formed from a single filament or a plurality of individual filaments grouped together. Yarn may also include separate filaments formed from different materials, or the yarn may include filaments that are each formed from two or more different materials. Similar concepts also apply to yarns formed from fibers. Accordingly, yarns may have a variety of configurations that generally conform to the definition provided above.
The various techniques for mechanically-manipulating yarn into a textile include interweaving, intertwining and twisting, and interlooping. Interweaving is the intersection of two yarns that cross and interweave at substantially right angles to each other. The yarns utilized in interweaving are conventionally referred to as warp and weft. Intertwining and twisting encompasses procedures such as braiding and knotting where yarns intertwine with each other to form a textile. Interlooping involves the formation of a plurality of columns of intermeshed loops, with knitting being the most common method of interlooping.
One challenge faced by athletes when competing or training, particularly in moderate to hot temperature conditions, is heat. Not only must the athlete cope with heat from the external environment, but the athlete also must cope with heat generated within the body of the athlete as a result of physical exertion.
Substantial heat may be generated in an athlete's body as a result of physical activity and exertion. In general, the core temperature of a body rises with increased physical activity. Less than 25% of the energy created during physical activity is converted into work energy (e.g., energy used to move the body and/or resist an applied force). The remaining 75%+ of the created energy typically must be dissipated as released heat. The human body's most effective mechanism for dealing with excess heat is through evaporative cooling. When a core body temperature rises to a certain level, the body will start to sweat. When this liquid sweat evaporates, the physical conversion of the liquid to its corresponding gas form (i.e., the drying) draws heat from the nearest heat source. In the case of sweat, the nearest heat source is the skin. In this manner, sweating cools a person due to the evaporative cooling action as the sweat dries. This evaporation of sweat is dependent upon the water vapor pressure (or relative humidity) of the air in contact with the skin. Air movement also is an important factor. For example, ambient air gains humidity as it picks up moisture during the evaporation of sweat. In the absence of adequate air movement (ventilation), this humidified air becomes trapped in areas surrounding the skin, thus inhibiting the cooling provided by the continued evaporation of sweat. Failure to properly release and move heat away from the body during exercise in a warm environment can cause a dangerous rise in the person's body temperature, potentially resulting in adverse health consequences, such as heat exhaustion or heat stroke.